Info from FOI on CFS 6-minute walking test results in University College London Hospitals

[Tom Kindlon]

Somebody sent me this and said I could post it once I didn't mention their name

FOI/2017/215

 

[Keela Too]

Interesting.
So for the improvement range afterwards, lower boundary numbers are negative, meaning some patients got worse?
And I imagine that patients that dropped out were not included as there would only be "before" data in that case..

Also interesting that the numbers taking part seem quite low.

 

[NelliePledge]

Its like when I was a kid at school. if I hadn't done my homework I would hurriedly do a really sketchy attempt at break time so I didn't get told off for not handing it in.
2/10 not good enough

 

[Esther12]

And I imagine that patients that dropped out were not included as there would only be "before" data in that case..

Yes, annoying that they didn't include data on drop-outs.

 

[user9876]

The numbers are very low do they only have 22 patients a year or are the drop out levels very high?

They do say that testing is routine

 

[trishrhymes]

The 6 minute walk test is a pretty useless test for ME patients.

I bet they don't record the effect over the next few days on the patients who push themselves to walk further.

If you spend 6 weeks persuading patients they should ignore their symptoms and that exercise is good for them, it's hardly surprising that some will manage to push themselves to walk a bit further the next time.

How far a patient with mild ME can walk on the test day, will, I suspect, depend largely on how much activity they have undertaken in the few days leading up to the test - and how much energy they have already expended getting to the centre on the day.

It seems likely to me that patients will be aware that they will be taking the test again, and will make sure they are well rested so they can manage it - maybe even using a less tiring method to get to the test centre that day so they can do the test.

And, as others have pointed out, where are the figures for how many dropped out before this stage or were unwilling or unable to do the walk again, having had a set back after the first one?

I think the most interesting outcome of this FOI request is that they have admitted they don't do any of the other testing suggested by the person who asked for the data. Nothing that would show whether there is actually any real change in the patient's functioning.

They persist in making sure they only get meaningless results. That has to be deliberate, and is highly irresponsible.

 

[alex3619]

There is a known bias in the 6mwt in which people do better the second time due to familiarity. To allow for this they perform one or more dummy tests that are not recorded. If such dummy tests are not done the whole test is unreliable. I would however like to know if the typical bias is anything like the ranges of "improvement" shown.

This is also a reason to require controls before you can interpret the results.

It is also the case, as we know from at least one study using actometers, that patients might well rest most of the time so they can produce brief bursts like in this test, but are doing less overall.

 

[Sean]

Those mean improvement numbers (range 46-82m) are better than the best (and only significant) PACE results on the same test (35-41m).

But not by much. And that is before we look at patient selection; small sample sizes (which gives greater epistemological weight to the more modest results from PACE due to its much larger sample sizes); lack of control group comparison; lack of long-term follow-up; and other methodological matters.

So, only a marginal improvement at best, that still leaves patients with absolute scores approximately half their age predicted, and down alongside some of the sickest patients from any disease that medicine deals with.

Just like PACE.

Hardly a ringing endorsement of the therapeutic model, is it.

 

[Jonathan Edwards]

The 6 minute walk test is a pretty useless test for ME patients.

I bet they don't record the effect over the next few days on the patients who push themselves to walk further.

...
And, as others have pointed out, where are the figures for how many dropped out before this stage or were unwilling or unable to do the walk again, having had a set back after the first one?

I think the most interesting outcome of this FOI request is that they have admitted they don't do any of the other testing suggested by the person who asked for the data. Nothing that would show whether there is actually any real change in the patient's functioning.

They persist in making sure they only get meaningless results. That has to be deliberate, and is highly irresponsible.

I think we need to be careful not to make inappropriate criticisms based on this release of information - a comment not necessarily directed at @trishrhymes.

The numbers are small and perhaps incomplete (nothing about dropouts) simply because this is what was asked for (documented changes - other baselines were not asked for) This was not a study as I understand it. It is just release of clinical information. I suspect that it was authorised by a helpful clinician who may be as sceptical about exercise therapy as any of us. We should not expect any placebo effect or massaging of data here because we have no indication that these are data designed to prove a point. They are just logs of clinical progress. They might be overoptimistic or over pessimistic. This is probably the only test used because the NHS is grossly overstretched and there is no justification for doing anything more - or even this. For individual treatments measuring the benefit is not necessary. If there was improvement then the patient will know. Presumably this is an attempt at some sort of audit for internal purposes. That might include wishful thinking but maybe the clinician is noting the modest nature of the improvement and wondering how they can find something better. Nobody managing ME/CFS at UCLH that I know of is under any illusion that exercise cures it. They are keen to find something that works.

If we are going to criticise PACE for being uninterpretable then surely we should accept that these data are even more completely uninterpretable - either way - as indicators of treatment efficacy. Those who live in orchards should not cherry pick!!

 

[Jonathan Edwards]

That said, I think these figures are worth having to look at, as much as anything because they are not clouded by being a 'study'. The documentation of some worsening might be noteworthy. But it disappears in 2015, which might be for various reasons.

 

[trishrhymes]

I think we need to be careful not to make inappropriate criticisms based on this release of information - a comment not necessarily directed at @trishrhymes.

The numbers are small and perhaps incomplete (nothing about dropouts) simply because this is what was asked for (documented changes - other baselines were not asked for) This was not a study as I understand it. It is just release of clinical information. I suspect that it was authorised by a helpful clinician who may be as sceptical about exercise therapy as any of us. We should not expect any placebo effect or massaging of data here because we have no indication that these are data designed to prove a point. They are just logs of clinical progress. They might be overoptimistic or over pessimistic. This is probably the only test used because the NHS is grossly overstretched and there is no justification for doing anything more - or even this. For individual treatments measuring the benefit is not necessary. If there was improvement then the patient will know. Presumably this is an attempt at some sort of audit for internal purposes. That might include wishful thinking but maybe the clinician is noting the modest nature of the improvement and wondering how they can find something better. Nobody managing ME/CFS at UCLH that I know of is under any illusion that exercise cures it. They are keen to find something that works.

If we are going to criticise PACE for being uninterpretable then surely we should accept that these data are even more completely uninterpretable - either way - as indicators of treatment efficacy. Those who live in orchards should not cherry pick!!

I take your points, @Jonathan Edwards. You are right to point out this is not a study, but data recorded, probably for internal audit. I guess my main criticism, recognising that funding is tight, and time is limited, would be that the 6 minute walk test is not a useful or valid test for finding out whether the 'treatment' is working, for the reasons I stated. I therefore wonder why they chose this particular test as their audit measure.

Given funding limitations, I can see that they cannot supply all patients with an actometer like a fitbit, or carry out 2 day CPET tests, but you can buy simple pedometers for about £5. These could be handed out at the first visit and patients asked to wear them and write down their daily totals along with a simple numerical score rating the level of their ME symptoms.

This would at least have the benefit of seeing whether patients are actually changing their behaviours and enable both patients and clinicians to assess the effects of increased activity over the time period of their treatment. Weekly averages of these scores could be calculated and plotted as a graph for each patient, so they and the therapist can see at a glance the pattern of activity and symptoms. This is something the patients could be shown how to do for themselves, enabling them to monitor their progress after the 6 week course is finished.

When my daughter attended group sessions for ME patients run by OT's some years ago, she was asked to fill in daily activity diaries and hand them in. There was no feedback from this, so it seemed entirely pointless, and she found it arduous and unhelpful. Writing down two numbers (steps and symptom score) at the end of each day would have been far more manageable and useful both to her and to the people running the 'treatment'.

 

[Jonathan Edwards]

Yes, that would be my general line of thought too, @trishrhymes. Maybe someone checking this thread is under UCLH and could take feedback to the physicians. The ones I know would be interested. I guess the problem with actometers is that you have to have a budget and a form to fill in to order them and then find out where they have been misdelivered to when you have eventually got approval to buy them and then they keep getting lost and the cupboard where they are kept is thrown out and ... all the usual things that happen in an NHS department. Exactly as they do in my daughter's maths department at the school where she teaches. But sometimes you can find a way that works!

 

[trishrhymes]

Yes, that would be my general line of thought too, @trishrhymes. Maybe someone checking this thread is under UCLH and could take feedback to the physicians. The ones I know would be interested. I guess the problem with actometers is that you have to have a budget and a form to fill in to order them and then find out where they have been misdelivered to when you have eventually got approval to buy them and then they keep getting lost and the cupboard where they are kept is thrown out and ... all the usual things that happen in an NHS department. Exactly as they do in my daughter's maths department at the school where she teaches. But sometimes you can find a way that works!

Ha ha, yes, as an ex maths teacher myself, I sympathise with your daughter. I think if I were in that position I would probably do what I used to do when teaching sometimes - buy the stuff myself! If they really do have so few patients as the data indicate, they could simply go on Amazon and buy a couple of dozen pedometers, then ask the patients to pay for them!

 

[alex3619]

I think there is subtle pressure to use cheap tests, and the 6mwt is exactly that. However actometers are reusable and require minimal supervision of patients. So I think a cost benefit case could easily be made to use them. Some of the other tests we might want to use such as the repeat CPET are very expensive by comparison, require expensive equipment with dedicated facilities, and risk further costs if the patient relapses as a result of CPET.

When you ask for data you can only get what they have. However, while not a study, when trying to interpret what these results mean all the caveats and requirements that go into interpreting a study are still useful.

The value lies in determining what is actually being done, and so highlighting where improvements can occur. It also gives a clue as to why such data does not easily refute rehab claims by proponents of CBT/GET, at least from their point of view. That however is only minimally related to regular clinical data. I have no doubt that many clinicians will, though perhaps without commenting much, be unhappy with the level of improvement even under such limited testing.

 

[Jonathan Edwards]

I think there is subtle pressure to use cheap tests, and the 6mwt is exactly that. However actometers are reusable and require minimal supervision of patients. So I think a cost benefit case could easily be made to use them.

I guess you never worked in public services, Alex? The pressure is not subtle, it is like a scrap metal compressor. You might think you could buy things but if you have no budget for anything not on a list, you can't. If you have no office, as is the norm now, there is nowhere even to store equipment. Physio staff come and go by the week so within a couple of months nobody will know where the actometers are.

 

[Valentijn]

That might include wishful thinking but maybe the clinician is noting the modest nature of the improvement and wondering how they can find something better.

If they were tracking the data to use it to make changes, they probably would have abandoned CBT/GET after the first few years of failures

 

[user9876]

I guess you never worked in public services, Alex? The pressure is not subtle, it is like a scrap metal compressor. You might think you could buy things but if you have no budget for anything not on a list, you can't. If you have no office, as is the norm now, there is nowhere even to store equipment. Physio staff come and go by the week so within a couple of months nobody will know where the actometers are.

Its not just public services large companies are very similar (I've worked in both).

 

[HowToEscape?]

I can't even summon enough patience to calmly sort out, then explicate the layers of BS, ^%$#**, ##### and & ₦₦₦₦₦ in the use of a six minute walking test as a measure of normal fitness, even less as a diagnostic test for our disease. Why, it is almost as if a test were designed to obscure rather that uncover our condition.

But strike the words 'almost' and 'if'.

 

[HowToEscape?]

I guess you never worked in public services, Alex? The pressure is not subtle, it is like a scrap metal compressor. You might think you could buy things but if you have no budget for anything not on a list, you can't. If you have no office, as is the norm now, there is nowhere even to store equipment. Physio staff come and go by the week so within a couple of months nobody will know where the actometers are.

Well, if a public service has not an office, not the relevant equipment and not continuity of staff, then it will not provide service. It will produce only the bureaucratic simulation of service.

 

[Mark Vink]

A number of important issues have been raised by previous commentators but maybe this might be helpful as well.

The 6MWT provides a good representation of a patient’s ability to perform submaximal activities of daily living and may be useful in serial evaluation of patient status and/or response to therapeutic interventions.

According to Wise et al., for improvements to reach statistical significance, an increase of at least 86 m is required.

If you walk 400 metres or less you would be ill enough to be on the waiting list for a lung transplant.

Patients with ME, who at baseline can walk 450 to 500 m are only mildly affected and are unlikely to get PEM from walking for only six minutes at a pace they can set themselves. These are also the sort of patients that usually will have a better second test regardless of therapy.